For petroleum contaminants such as BTEX (benzene, toluene, ethylbenzene, xylenes), natural bacteria generally can degrade them into harmless compounds in appropriate environmental conditions. This process is usually oxygen demand. However, the aquifer mostly is oxygen deficit that slows or even stops the biodegradation process. If additional oxygen can be offered sufficiently into aquifer, the aerobic process can be reactivated.
As it has been known, using oxygen-releasing compounds (ORCs) (for example, magnesium peroxide, calcium peroxide and so on) to deliver oxygen could be a cost-effective way for soil and groundwater remediation, because it is a water-driving process without the need of powder. In real applications, however, pure magnesium peroxide or calcium peroxide reacts with water so fast that bacteria cannot utilize the produced oxygen in time.
According to prior research studies, pure ORCs could be turned into time-released compounds by the intercalation of phosphate into the crystal structure of ORCs. This method still produces original powder-type ORCs which can be used as a slurry and injected by press into aquifer or suspended in wells by so-called “socks” holders. Such powder type and delivering ways, however, are facing several issues. For example, ORC powders are hard to be dispersed in aquifer that caused oxygen distribution not evenly; the end products [ex. Ca(OH)2] can not be withdrawn from aquifer, which caused higher pH (>10) in groundwater.
Therefore, in terms of ORCs' time-release technology, material type, and delivery, it should be necessary to provide a better method that can be used to manufacture tunable time-release ORCs and can generate more cost-effective and environment-friendly delivery for ORCs.